Figure 4.

Cryosections of tibialis anterior muscles were triple-stained with Alexa 594-conjugated α-BT (red), mouse anti-rapsyn mAb1234 (green), and rabbit anti-VAChT (blue); merge on the right. A: In an untreated tibialis anterior muscle of a control rat AChR, rapsyn and VAChT are co-localized at the endplates. B: In the contralateral rapsyn-treated muscle of the same animal, rapsyn is localized extrasynaptically in the cell membrane of a transfected fiber (arrowhead). In this fiber, the endplate contains an increased amount of rapsyn (arrow). C: In untreated chronic EAMG muscles, endplates showed reduced staining of AChR and rapsyn but not VAChT. D: In rapsyn-treated EAMG muscles, the endplates in fibers with high amount of extrasynaptic rapsyn aggregates had a staining intensity of AChR and rapsyn that was similar to endplates of untreated control muscles (arrowhead). D: In other fibers without such aggregates, endplates had a reduced staining intensity for AChR and rapsyn (arrow). E: Extrasynaptic AChR co-localized with rapsyn (arrowheads) adjacent to the NMJ (arrow) in the membranes of transfected fibers. Scale bars = 100 μm.